This invention generally relates to cathode ray tubes (CRTs), and more particularly, to a shadow mask frame assembly for CRTs that eliminates the use of separate corner brackets for supporting the frame assembly within CRTs.
A color cathode ray tube, or CRT, includes an electron gun for forming and directing three electron beams to a screen of the tube. A shadow mask, which may be either a formed mask or a tension mask having strands, is located between the electron gun and the screen. The electron beams emitted from the electron gun pass through apertures in the shadow mask and strike the screen causing the phosphors to emit light, so that an image is displayed on the viewing surface of the faceplate panel.
Present CRTs use steel frames to support the shadow mask within the faceplate panels of the tubes. Typically, such frames incorporate two long sides to which the mask is attached, two short sides perpendicular to the long sides and four corner brackets. The short sides are open at the ends, and a substantially flat corner bracket is used to provide the required strength in each corner. All parts are typically assembled by welding.
Because a plurality of parts and extensive welding is employed to make the frame, the ability to control the initial dimensions of the frame at fabrication, as well as dimensional changes during mask/frame assembly and processing, is extremely difficult. Additionally, dimensional inaccuracies affect the ability to attach springs or clips that support the frame in the proper location and orientation.
It is desirable to develop a mask frame assembly that reduces complexity and material usage of the frame without compromising the strength of the frame. Reducing the number of parts and the associated welding will improve the dimensional control of the frame at fabrication, reduce the propensity for dimensional changes during mask/frame assembly and processing, and reduce cost. Further, facilitating in-situ forming of the clip/spring attachment zone will improve the reliability of the structural detail.
This invention relates to a CRT having a tension mask frame assembly comprising a substantially rectangular support frame having two long sides, two short side, four corners and a tension mask attached to the two long sides of the support frame. The assembly includes closed ends at each of the corners, wherein the closed ends are contiguous with one of the adjacent sides at respective corners and each of the closed ends has a plurality of walls forming a closed corner portion between the long side and the short side of the support frame and including an angled mounting wall for use in suspending the mask within the color cathode ray tube.